These don’t come up that often - if you have an 05-09 system you are planning on gutting and replacing with an Android unit this is the amp you need - if you buy the correct harness and do a simple rep in it plays really nicely with original speakers and sun sounds far better believe it or not

https://www.ebay.co.uk/itm/333970732881 Current stable:
2006 BMW M6
2007 4.2 V8 S/C FF
Gone:
2002 4.4 V8 FF